Marine conductor pipe assembly



Dec. 7, 1965 0. DE VRIES ETAL 3,221,317

MARINE CONDUCTOR PIPE ASSEMBLY Filed Sept. 13, 1962 6 Sheets-Sheet 2 F 2INVENTORS D. DE VRIES F. POORMAN.JR. BY

THEIR AGENT Dec. 7, 1965 D. DE VRIES ETAL MARINE CONDUCTOR PIPE ASSEMBLY6 Sheets-Sheet 5 Filed Sept. 13, 1962 INVENTORS 0. DE VRIES R. m J. E NG A u A M R R O H H O H P F Dec. 7, 1965 0. DE VRIES ETAL 3,221,317

MARINE CONDUCTOR PIPE ASSEMBLY Filed Sept. 13, 1962 e Sheets-Sheet 5 IIOINVENTORS F|G.8 D. DE VRIES F. POORMAN,JR.

THEIR AGENT United States Patent 3,221,817 MARINE CONDUCTOR PIPEASSEMBLY Douwe de Vries, Metairie, and Frank Poorman, Jr., Lafayette,La., assignors to Shell Oil Company, New York, N.Y., a corporation ofDelaware Filed Sept. 13, 1962, Ser. No. 223,396 7 Claims. (Cl. 16666.5)

This invention relates to apparatus for use in drilling, completing andworking-over operations in oil and gas wells at offshore locations, andpertains more particularly to apparatus adapted to provide full-flowfluid communication between a vessel at the surface of a body of waterand a wellhead assembly positioned on the ocean floor or at asubstantial depth below the surface of the water.

In an attempt to locate new oil fields, an increasing amount of welldrilling has been conducted at oifshore locations, such for example, asoff the coast of Louisiana, Texas and California. As a general rule, thestrings of casing in a well, together with the tubing strings or string,extend to a point above the surface of the water where they are closedin a conventional manner that is used on land wells, with a conventionalwellhead assembly being attached to the top of the casing. Recently,methods and apparatus have been developed for drilling and completingwells wherein both the well casinghead, and subsequently the wellheadassembly and casing closure device, are located under water at a depthsufficient to allow ships to pass over them. Preferably, the casingheadand the wellhead closure assemblies are located close to the oceanfloor. In order to install well drilling equipment underwater at depthsgreater than the shallow depth at which a diver can easily operate, ithas been necessary to design entirely new equipment for this purpose.

Wells drilled in deep water are generally drilled from vessels ofvarying designs commonly known as drilling barges, vessels or platforms.Deepwater wells are generally drilled by one of two methods. In onemethod the string of drill pipe extends downwardly from the drillingbarge to the drilling wellhead assembly on the ocean floor which isclosed at the top by a circulation head with a flexible hose runningfrom the circulation head back to the surface and to the drilling bargeso that drilling fluid may be circulated down the drill pipe, throughthe drill bit, and thence upwardly on the outside of the drill pipe, outthe circulation head and up the flexible hose to the barge again. In thesecond method, a large-diameter pipe known as a marine conductor pipe isput together and arranged to extend from the drilling wellhead assemblyon the ocean floor to the barge on the surface of the water. In thelatter method, the drill pipe rotates within the conductor pipe withdrilling fluid being circulated down through the drill pipe, through thebit at the bottom thereof, up the outside of the drill pipe and thenceupwardly through the annular space between the conductor pipe and thedrill pipe, returning to the barge in the conventional way. The presentinvention is concerned with apparatus to be used in the second methoddescribed hereinabove.

One of the problems in drilling underwater wells from floating barges isthat of providing suitable means for suspending and/ or securing amarine conductor pipe assembly in movable relationship to the drillingbarge so that the barge is free to move up and down with the movement ofthe water while the marine conductor pipe assembly is fixed againstvertical movement while being arranged to be moved laterally in anydirection. Some of the presently designed marine conductor pipeassemblies have been provided with buoyancy tanks supplying a positivebuoyancy to the marine conductor pipe assembly so that the assembly isvertically positioned in the Patented Dec. 7, 1965 ice water with itslower end locked to an underwater wellhead. A marine conductor pipe orassembly of positive buoyancy has certain drawbacks in that, in theevent that the connection between the lower end of the conductor pipeand the wellhead is broken, the conductor pipe would shoot upwardly inthe water underneath or adjacent the barge and possibly damage thefloating drilling barge or rupture some of its buoyancy tanks.

It is therefore a primary object of the present invention to provideapparatus for supporting a marine conductor pipe assembly adjacent to abarge without the possibility existing of the marine conductor pipebreaking loose from an underwater wellhead and/ or the barge anddamaging the barge.

A further object of the present invention is to provide apparatusindependent of the barge for supporting the major portion or weight of amarine conductor pipe assembly while the rest of the assembly issupported by the barge itself.

Another object of the present invention is to provide weight-supportingapparatus on a floating drilling barge which may be readily adjusted tosupport a portion of the weight of a marine conductor pipe assembly asthe weight of the portion varies due to changes in drilling operations,such for example, as due to a change in the weight of the drilling mudbeing circulated through the assembly.

Still another object of the present invention is to provide a marineconductor pipe assembly including apparatus for controlling and/orkilling a well from a point above the surface of the water whenemergency conditions are encountered in the drilling of a well.

A further object of the present invention is to provide a marineconductor pipe assembly with suflicient flexibility whereby in roughweather a drilling Vessel or barge may move several degrees in anydirection off the center line of a well that is being drilled withoutrupturing the marine conductor pipe assembly.

These and other objects of this invention will be understood from thefollowing description taken with reference to the drawings wherein:

FIGURE 1 is a diagrammatic view taken in longitudinal projectionillustrating a floating drilling vessel positioned at the surface of theocean with an underwater wellhead assembly positioned on the oceanfloor;

FIGURE 2 is a diagrammatic view taken in longitudinal projection and inenlarged detail of the lower portion of the drill rig and the upperportion of the marine conductor pipe assembly shown in FIGURE 1;

FIGURE 3 is a cross-sectional view taken along the line 3-3 of FIGURE 2;

FIGURE 4 is a longitudinal view taken in enlarged detail of one of thecounterweights or ballast tanks of FIGURE 2;

FIGURE 5 is a cross-sectional view taken along the line 5-5 of FIGURE 4;

FIGURE 6 is a longitudinal view in enlarged detail of one of thebuoyancy tanks surrounding the marine conductor pipe of FIGURE 1;

FIGURE 7 is a longitudinal view of the other buoyancy tank shown inFIGURE 1;

FIGURE 8 is a longitudinal view illustrating the manner in which theupper ends of auxiliary pipes running along the outside of the marineconductor pipe are secured thereto;

FIGURE 9 is a cross-sectional view taken along the line 9-9 of FIGURE 8;

FIGURE 10 is a view taken in partial cross section of one form of a pipeguide and support member by which auxiliary pipes may be secured to themarine conductor pipe of the present invention;

. cemented therein.

FIGURE 11 is a plan view of the apparatus in FIG- URE and,

FIGURES 12A, 12B and 12C are longitudinal views adapted to be arrangedend to end to show in enlarged detail the marine conductor pipe assemblyof the present invention as it is positioned on a wellhead of the oceanfloor.

Referring to FIGURE 1 of the drawing, a drilling barge or platform isgenerally represented by numeral 11.. The drilling barge or platform 11is of any suitable type preferably one, as illustrated, floating at thesurface of a body of water 12 and substantially fixedly positioned overa preselected drilling location by suitable barge positioning means orby being anchored to the ocean floor 13 by suitable anchors 14a and 15aconnected to the anchor lines 14 and 15. Equipment of this type may beused when carrying on well drilling operations in water depths varyingfrom about 100 to 1500 feet or more. The drilling barge is equipped witha suitable derrick 16 as well as other auxiliary equipment needed duringthe drilling of a well such as a hoist system 17, rotary table 18, etc.The derrick 16 may be positioned over a drilling slot or well whichextends vertically through the barge in a conventional manner. Whenusing the equipment of the present invention the slot of the barge maybe centrally located or extend in from one edge. However, drillingoperations may be carried out over the side of the barge or vesselwithout the use of a slot, as from a portion of the deck of the bargewhich is cantilevered out over one end, as is the case in the barge inFIGURE 1.

As shown in FIGURE 2, a portion of the barge deck 20 is cantilveredtoward the viewer on support beams 21 and 22 which are supported bydiagonal braces 23 and 24 from vertical support members 25 and 26 of thebarge. Suspended beneath the cantilevered portion 20a of the barge deck20 is a craneway made up of tracks 27 and 28, and intermediate deck 30and a spider deck 31. The decks 20a, 30 and 31 are all positioned belowthe derrick 16 which is provided with an elevated rig floor or operating platform 32.

A typical underwater wellhead structure, generally represented bynumeral 34 in FIGURE 1, is illustrated as comprising a base member 35which is positioned on the ocean floor 13 and fixedly secured to aconductor pipe or a large diameter well casing 36 which extends downinto a well which has been previously drilled, and is preferably Thus,the base structure or member 35 is rigidly secured to the ocean floor inorder to support two or more vertically-extending guide columns 37 and38 (FIGURE 12C) adapted to receive and guide therein guide arms 40 and41, 40a and 41a, and 40b and 41b which are arranged to slide alongvertically extending guide cables 42 and 43. The lower ends of the guidecables 42 and 43 are anchored to the base structure 35 within the guidecolumns 37 and 38, while extending upwardly through the water to thedrilling barge 11 where they are preferably secured to constant tensionhoists (not shown). If desired, a single guide cable extending betweenthe base structure 35 and the vessel 11 may be employed to position apiece of equipment on the wellhead. Generally, a guide system having atleast three guide cables is preferred. However, it is to be noted thatwellhead equipment could be lowered from the vessel 11 down to thewellhead by methods other than using the guide cable system illustrated.

Centrally positioned above the base member 35 and fixedly securedthereto, or to the conductor pipe 36, is a well casinghead unit 44 whichmay be provided with a cement circulation or fluid return line 45 whichmay be selectively closed by a remotely operated valve 46. The

guide arms 40 and 41 are illustrated as being connected to a wellheadconnector unit 47 which may be hydraulically or electrically actuated toconnect to the top of the application Serial No. 105,068, filed April24, 1961. In the above-identified patent application, a wellheadconnector 47 is provided with a self-contained electro-hydraulicoperating unit which is provided with operating power from an electricaltransmission line (not shown) running to the barge 11 at the surface.Alternatively, the wellhead connector could be hydraulically operated bymeans of a pressure fluid line (not shown) running to the barge 11.

During the drilling of a well, one or more blowout preventers areconnected coaxially above the wellhead connector 47. In FIGURE 12C aseries of three blowout preventers 50, 51, and 52 are illustrated asbeing fixedly secured together and forming a unitary package with thewellhead con-nector 47, which package .is adapted to be lowered onto thecasinghead 44 in any suitable manner. Preferably, the combined blowoutpreventers 50, 51 and 52 and the wellhead connector 47 are run togetherinto position on the top of the well by being lowered through the waterfrom the drilling vessel 11 by means of a pipe string (not shown),commonly known as a running string, with the lower end of the runningstring being connected to the uppermost blowout preventer 52 by anysuitable coupling or connector which may be similar in form to thewellhead connector 47. During drilling operations the running string isreplaced by a larger diameter pipe known as a marine conductor pipe andis represented generally in the drawing by numeral 53.

The various wellhead components, such for example as the wellheadconnector 47 and blowout preventers 50, 51 and 52 may be eitherhydraulically, pneumatically, or electrically actuatable but arepreferably actuatable with each unit being provided with anelectro-hydraulic operator unit as described in copending patentapplication Serial No. 105,068, filed April 24, 1961. Alternatively, theblowout preventers 50, 51 and 52 could be provided with pressure hoses(not shown) which would extend up through the water to the drillingbarge 11.

In addition, the drilling assembly stack of blowout preventers 50, 51and 52 on the top of the wellhead connector 47 is provided with one orpreferably two small diameter conduits which will be termed hereinbelowas choke and kill lines 54 and 55, respectively. The choke and killlines 54 and 55 are employed to provide means for establishing fluidcommunication between the drilling vessel 11 and the well duringdrilling operations after one or more of the blowout preventers 51 and52 have been closed during an emergency. The choke and kill lines 54 and55 are provided with remotely actuatable valves 56 and 57, respectively,which are actuated through pressure hoses or electrical transmissionlines (not shown) which extend to the surface. Since these valves andthe blowout preventers and the wellhead connector 47 do not form anessential part of the present invention and are described in detail inthe above-identified copending application, they will not be furtherdescribed here.

A marine conductor pipe assembly is employed in drilling underwaterwells in order to establish unrestricted communication with the well ina manner shown and described in US. Patent 2,606,003, which was issuedAugust 5, 1952, to J. M. McNeil]. The marine conductor pipe is ofsuflicient diameter that a drill pipe and drill bit at the lower end ofthe drill pipe can be run down through the marine conductor so as tobore into the ocean floor. Thus, the annular space between a drill pipeand the inner wall of a marine conductor pipe forms a full flow passagefor return of fluid to the drilling barge together with cuttings removedfrom the bottom of the well by the bit. Drilling mud would be pumpedentirely in the conventional way by means of a pump from the barge downthe drill string (not shown), out the drill bit, up the space outsidethe drill pipe in the well to the wellhead on the ocean floor, andthence upwardly through the casinghead, blowout preventers and upthrough the marine conductor 53 outside the drill pipe to the barge 11.

The marine conductor pipe assembly, generally represented by numeral 53in FIGURE 1, is shown in FIGURES 12A, 12B and 12C in greater detail,FIG- URE 12B representing an upward extension of FIG- URE 12C and FIGURE12A representing an upward extension of FIGURE 12B. It is to beunderstood however that the overall length of the marine conductor pipeassembly may vary from 100 to 1500 feet or more while the width of theassembly need not become any greater. In order to facilitate handling ofthe marine conductor pipe assembly of the present invention on adrilling vessel, and to aid in the assemblying or construction of themarine conductor pipe so that it extends from the drilling vessel 11(FIGURE 1) to the uppermost blowout preventer 52 of the drilling stack(FIGURE 12C), the marine conductor pipe assembly 53 is made up in anumber of sections, the pipe sections generally being from to 40 feetlong.

The lowermost section of the marine conductor pipe assembly comprises alarge diameter pipe 60 having fixedly secured to its lower end a landinghead or pipe connector 61 of a size and having a bore to fittelescopically onto and to make a sealing engagement with a landingmandrel 62 which is fixedly secured at its lower end to the uppermostblowout preventer 52, and extends upwardly and coaxially therefrom. Ifdesired, a pipe joint locator 63 may be provided in the conductor pipeassembly above the landing head 61.

Extending upwardly along the large-diameter conductor pipe 60 are atleast one and preferably two small-diameter pipes which in this case areextensions of the choke and kill lines 54 and 55, respectively. It is tobe understood that these small-diameter pipes 54 and 55 are also made upfrom short pipe sections which are coupled together in any suitablemanner, as by screw threads or other couplings, it being preferred thatthe coupled joints are flush on the outside with the connectors or tooljoints having the same outside diameter as that of the pipe. The chokeand kill lines 54 and 55 are aligned with the marine conductor pipe 60by means of a series of guide and support arms or brackets generallyrepresented in FIGURES 12A, 12B and 12C by numeral 64. One form of asuitable guide and support arm 64 is shown in FIGURES 10 and 11. Asillustrated, the pipe support bracket 64 comprises a short section oflarge-diameter pipe which is split longitudinally and hinged at 66 whilebeing connectible on the opposite side by bolts 67. The internaldiameter of the pipe section 65 is equal to the outside diameter of themarine conductor pipe 60 and serves in the way of a clamp. A pair ofdiametricallypositioned arms 68 and 69 extend outwardly from the pipesection 65 With small-diameter pipe guides 71 and 72 being fixedlysecured, as by Welding to the ends of the arms 68 and 69. The pipeguides 71 and 72 consist of short sections of small-diameter pipeslightly larger than the choke and kill lines 54 and 55 so that the pipeguides 71 and 72 are able to slide up and down the pipes 54 and 55 whenengaged around them. For ease in attaching the pipe guides to the chokeand kill lines, the pipe guides 71 and 72 also may consist of split pipesections provided with hinge pins 73, and connector pins 74. Anysuitable spacing may be employed between the support arms 64. Generally,a support arm or bracket 64 is positioned above each tool joint or everyother tool joint of the marine conductor pipe 60, depending upon thelength of the pipe sections of the marine conductor pipe.

As shown in FIGURE 1 and FIGURES 12A and B, the marine conductor pipe 60is provided with a buoyancy member or chamber in the form of one or moreconcentrically arranged buoyancy tanks 76 and 77 which, for ease ofhandling, are preferably no greater in length than one section of themarine conductor pipe 60. As shown in FIGURES 6 and 7, the tanks 77 and76 may be provided with internal reinforcing members 78. The

number and size of the buoyancy tanks 76 and 77 to be used wouldnaturally depend upon the weight of the marine conductor pipe 60 and thechoke and kill lines 54 and 55 to be supported. The weight of theseelements 54, 55 and 60 in turn depends upon the depth of the water atwhich a well is being drilled as well as the size of these elements andthe material of which they are made. Whatever amount of weight exists tobe supported by these buoyancy tanks, it is extremely important, inaccordance with the teachings of the present invention, that thebuoyancy tanks together with the marine conductor pipe assembly to whichthey are attached have a negative buoyancy. That is, in the event thatthe marine conductor pipe assembly broke loose at the blowoutpreventers, the buoyancy tanks 76 and 77 would not have suflicientflotation capacity to cause the marine conductor pipe to float to thesurface thus obviating any chance of the marine conductor pipe assemblydamaging the drilling vessel. It is preferred, however, that thecombined buoyancy tanks and conductor pipe assembly have only a slightlynegative buoyancy. Thus, the buoyancy tanks are preferably designed soas to support the major portion of the weight of the marine conductorpipe assembly below them.

The remaining weight portion of the marine conductor pipe assembly issupported at the vessel by means of suitable cables 80 and 81 which arefixedly secured at one end to the upper movable end 82 of the conductorpipe 60. In the particular arrangement of equipment shown the upper end82 of the conductor pipe 60 is provided with a telescopic joint in thefor-m of a section, say 25 feet long, of large-diameter pipe 83 in whicha smaller-diameter pipe 84 is mounted for sliding vertical movementthrough a seal (not shown) carried in the upper end 82 of the conductorpipe. The upper end of the small diameter pipe 84 may be provided with abumper section 85 and a bell nipple 86 from which a side conduit 87allows mud to flow to suitable mud tanks (not shown). The bell nipple 86is concentrically positioned beneath the rotary table 18 and issupported in place together with the small-diameter pipe portion of theitelescopic sub by means of support chains or cables 8 an 9.

As shown in FIGURES 2 and 3 the cables 80 and 81 which extend from theupper end 82 of the telescopic joint section 8, are lead over suitablesheaves or pulleys. Thus, cable 80 passes over sheaves 88, 89 and 90with the opposite end of the cable being connected to a counterweight91. Cable 81 in turn passes over sheaves 92, 93 and 94 and the lower endof the cable is secured to the top of counterweight 95. Cables 80 and 81may each actually represent a number of parallel cables, depending onthe loads imposed.

A preferred form of counterweight is shown in FIG- URES 4 and 5 of thedrawing as comp-rising a pair of open-topped tanks, each tank orcounterweight 91 (FIGURE 5) being provided with lateral movementlimiting means in the form of vertically-arranged oak runners 96 onopposite ends of the tank 95, the runners being adapted to slidevertically along angle-iron guide rails 97 which form an elevator shaft(FIGURE 4) in which the counterweight tank rises and falls as thedrilling vessel 11 and support member 25 rises and falls with the motionof the Water, thus enabling a constant tension to be maintained bycables 80 and 81 on the top of the marine conductor pipe assembly tosupport that portion of the weight thereof that is not supported by thebuoyancy tanks 76 and 77. The contact surface of the oak runners 96 iskept heavily greased at all times. The counterweight tank 91 (FIGURE 5)is provided with one or more vertical bafl'le plates 98 to reduce themovement of the water laterally in the tanks while the bottom of theplates 98 are provided with openings therethrough (not shown) so thatthe level of water in the tank '91 can equalize after filling. Each tankis also of the mandrel 62.

provided with a suitable drain port 99 and shut-off valve 100. The oakrunners are secured to the outside of the tank 91 by suitable bolts 101and are replaceable when worn. The end of the cable 81 is secured to thetop center of the tank by bolt 102 (FIGURE 4). The vertical length ofthe elevator rails 97 may be in the order of 20 feet or more dependingupon the estimated rise and fall of the drilling vessel 11 and hence themovement of the counterweight tanks 91 and 95 during drillingoperations. Horizontal cross members 103 and 104 are provided at thelower end of the vertical elevator guide rails 97 so that thecounterweights 91 and 95 can be positioned thereon when not in use andwhen disconnected from the marine conductor pipe assembly. The amount oftension being applied to the counterweight cables 80 and 81 by thecounterweights 91 and 95 can be readily adjusted by adding more water tothe counterweight tanks 91 and 95 or draining it therefrom. Additionalweight may be obtained by the use of a Weighted fluid instead of water.

In FIGURE 12C one form of a landing head 61 is shown as being providedwith an outwardly flaring skirt 105 at its lower end to facilitateengagement with the upper end of the leading mandrel 62 when the formeris lowered onto the latter. A suitable seal 106 is carried within thelanding head 61 and is employed between the landing head 61 of themarine conductor pipe assembly and the landing mandrel 62 on the top ofthe blowout preventer 52. While a static seal could be employed in somecases, the sealing element 106 is preferably arranged within the landinghead 61 so that it can be expanded inwardly against the landing mandrel62 to form a fluidtight seal thereagainst. Alternatively, the landinghead 61 may be provided with locking dogs (not shown) and take the formof the wellhead connector 47. The inner surface of the skirt 105 of thelanding head 61 preferably forms a landing shoulder for resting inweightsupporting engagement on the top of the seating surface It is tobe understood that only a slight amount of weight is supported by thewellhead assembly. In so doing, the marine conductor string will remainseated on mandrel when the hydraulic connecting means fail. As describedhereinabove, the major por- 'tion of the weight of the marine conductorpipe assembly is supported by the buoyancy tanks with the rest valves 56and 57 in a suitable manner by any connector means well known to theart, as by safety joints 56a and 57a. Preferably, the connectors are ofthe type that may be disengaged remotely. The choke and kill lines 54and 55 are mounted in spaced relationship to the marine conductor pipe60 so that they are positioned outside the buoyancy tanks 76 and 77, asshown in FIGURES 12A and 12B, rather than having them pass through thetanks if the lines 54 and 55 were arranged closer to the conductor pipe60. In the event that the choke and kill lines pass through the buoyancytanks 76 and 77, it would be necessary to put sleeves longitudinallythorugh the tanks which were of a larger internal diameter than theoutside diameter of the choke and kill lines 54 and 55 so that the chokeand kill lines would be permitted to move vertically relative to theconductor pipe 60 and the buoyancy tanks 76 and 77 as the conductor vpipe was subjected to bending stresses during drilling operations.

The connections at the top of the choke and kill lines 54 and 55 areshown in FIGURE 8 and FIGURE 12A. In order to contain well pressures thechoke and kill lines are preferably made of rigid material of a strengthsufiicient to Withstand any well pressures encountered during drillingoperations. Although the choke and kill lines 54 and 55 are providedwith shut-01f valves 56 and 57 at the wellhead which may be remotelyclosed by an operator on the drilling vessel 11, these valves may besubject to failure or their conrtol lines may become ruptured. Thus, foremergency purposes the choke and kill lines 54 and are provided withshut-off valves 108 and 109 near the top thereof and at least above thewater surface so that these valves may be closed manu ally, ifnecessary. To enable an operator to close these valves 108 and 109 asmall platform 110 having a hand rail 111 is secured to the bottom of anattachment collar 112. As shown in FIGURE 9 the attachment collarcomprises a split pipe section being hinged at 113 and being providedwith suitable connector means, such for example as flanges 114 and 115which are secured together by bolts 116, so as to fixedly secure thecollar 112 to the upper end of the conductor pipe 60. The collar 112 isalso provided with a horizontally-disposed pivot pin 117 which pivotallysecures a pair of yoke arms 118 and 119 to the collar 112. The choke andkill lines are preferably supported by means of gimbal-mounted slips orany other suitable means of vertical support in the outer ends of theyoke arms 118 and 119. Thus, the choke line 54 (FIGURE 9) is verticallysupported and held down in a block 120 which is pivotally secured by apivot pin 121 to a surrounding frame 122 which is in turn pivotallysecured to the outer ends of the yoke arms 118 and 119 by means of pivotpin 123 which is arranged with its axis in a direction normal to theaxis of the pivot pin 121, both pivot pins 121 and 123 lying in ahorizontal plane. It will be seen that as the drilling vessel 11(FIGURE 1) moves off the vertical line 'of the well to cause the marineconductor pipe assembly to bend, the choke and kill lines 54 and 55 bendand the support yoke arms 118 and 119 (FIGURE 9) will adjust themselvesto eliminate introduction of any additional stresses into the kill andchoke lines 54 and 55 due to this condition.

In order to compensate for the rise and fall motion of the vessel, withwave action, relative to the upper end of the choke and kill lines 54and 55, the choke and kill lines 54 and 55 are provided above theirshut-off valves 108 and 109 with flexible pipe line sections of anysuitable type. As shown in FIGURES 8 and 12A the choke line is providedwith flexible couplings 124, 125, 126 and 127 which interconnect pipeline sections 128, 129, 130 and 131. In turn, the kill line 55 isprovided with flexible couplings 133, 134 and 135 which interconnectpipe lines 136, 137 and 138. The upper ends of pipe lines 131 and 138are provided with shut off valves 139 and 140 which are part of a moreor less conventional manifold. It is to be understood that the apparatusof the present invention may be modified in many ways while stillforming an operative combination. Thus, for example the choke line 54may be eliminated, it being sufficient in some cases that a single lineextend from the drilling vessel 11 to the wellhead below at least someof the blowout preventers whereby a heavy fluid can he injected into thewell in order to kill the well or to control the pressure therein inabnormally high pressure oil fields.

It will be seen that the apparatus of the present invention provides asimple marine conductor pipe assembly adapted to be readily installed orto be disconnected and withdrawn when the vessel is to move to anotherloca tion. The apparatus also provides means for suitably supporting oneor more rigid small-diameter pipes adjacent a large-diameter marineconductor pipe with the combination of pipes being buoyantly supportedto a large extent by buoyancy chambers. It is to be understood howeverthat the entire marine conductor pipe assembly is to have a negativebuoyancy under operating conditions so that there is no danger at anytime of the entire assembly breaking loose from the wellhead at theocean floor and fioatingto the surface in a manner so as to endanger ordamage the floating vessel 11. This is especially important since thestability and buoyancy of the drilling vessel 11 may depend upon arelatively thinskinned or buoyancy chambers which could be readilypunctured by a buoyant marine conductor pipe assembly shooting to thesurface. At the same time the apparatus of the present inventionprovides unique counterweights which are readily adjustable as tosupport capacity for maintaining constant tension on the upper portionof the marine conductor pipe assembly.

We claim as our invention:

1. Apparatus for drilling, completing and working over an underwaterwell, said apparatus comprising operational platform means positionedabove the surface of a body of Water,

a well base positioned below the surface of the water and includingsubstantially vertical well base pipe means having a lower portionthereof fixedly anchored to the formation below said body of water and aportion extending upwardly above said formation,

marine conductor means connectible at its lower end to the upper end ofsaid well base pipe means with the upper end of said conductor pipeextending above the surface of the water in the vicinity of saidoperational platform means,

buoyancy tank means secured to said marine conductor means below thesurface of the water and having sufficient buoyancy to support a majorportion of the weight of said marine conductor means, and

weight support means operatively secured to said marine conductor meansnear the upper end thereof and to said platform means for supportingthat portion of the weight of said marine conductor means unsupported bysaid buoyancy tank means,

a vertically-extending tubular member of said well base in communicationwith said well base pipe means,

a wellhead connector carried at the lower end of said marine conductormeans connectible to said tubular member,

small-diameter rigid conduit means extending from said operationalplatform means to said Well base,

conduit connector means securing the lower end of said conduit means tosaid well base in communication with the bore of said well base pipemeans,

and valve means in said conduit means near the upper end thereof andabove the surface of said body of water.

2. The apparatus of claim 1 including connector means securing saidconduit means to said marine conductor means at spaced intervalstherealong.

3. The apparatus of claim 2 wherein said connector means are fixedlysecured to said marine conductor means and slidably secured to saidconduit means to permit differential vertical movement of said conduitmeans relative to said conductor means when they are moved laterally.

4. The apparatus of claim 2 wherein said connector means are fixedlysecured to said conduit means and slidably secured to said conductormeans.

5. The apparatus of claim 1 including flexible pipe means in saidsmall-diameter conduit means above the valve means therein above thesurface of the body of water.

6. The apparatus of claim 2 wherein the uppermost connector meanscomprises movable yoke means, horizontal means securing said yoke meansto the marine conductor means near the upper end thereof, and gimbalmeans securing said movable yoke means to said conduit means.

7. Apparatus for drilling, completing and working over an underwaterwell, said apparatus comprising (a) operational platform meanspositioned above the surface of a body of water on a vessel,

(b) a well base positioned below the surface of the water and includingsubstantially vertical well base pipe means having a lower portionthereof fixedly anchored to the formation below said body of water and aportion extending upwardly above said formation,

(0) marine conductor means connectible at its lower end to the upper endof said well 'base pipe means with the upper end of said conductor pipeextending above the surface of the water in the vicinity of saidoperational platform means,

(d) buoyancy tank means secured to said marine conductor means below thesurface of the water and having suflicient buoyancy to support a majorportion of the weight of said marine conductor means,

(e) weight support means operatively ecured to said marine conductormeans near the upper end thereof and to said platform means forsupporting that portion of the weight of said marine conductor meansunsupported by said buoyancy tank means,

(f) said weight means carried by said vessel and arranged forsubstantially free vertical movement, sheave means secured to saidvessel at a fixed level above the uppermost position of said weightmeans, cable means having one end thereof secured to said marineconductor means, said cable means passing operatively over said sheavemeans with the other end of the cable means secured to said weightmeans, said weight means being free to move up and down as the vesselrises and falls due to wave action,

(g) movement-limiting means positioned in contact with said movableweight means for confining the mogement of said weight means along aselected r (b) said movement-limiting means comprising substantiallyvertically-extending rigid elongated members of a length at least equalto the maximum vertical movement of said weight means and arranged incontact with said weight means to prevent any substantial lateralmovement thereof, and

(i) said weight means comprising variable weight tank means adapted tocontain weighting material.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS7/ 1961 Great Britain. 8/1961 Great Britain.

CHARLES E. OCONNELL, Primary Examiner.

7. APPARATUS FOR DRILLING, COMPLETING AND WORKING OVER AN UNDERWATERWELL, SAID APPARATUS COMPRISING (A) OPERATIONAL PLATFORM MEANSPOSITIONED ABOVE THE SURFACE OF A BODY OF WATER ON A VESSEL, (B) A WELLBASE POSITIONED BELOW THE SURFACE OF THE WATER AND INCLUDINGSUBSTANTIALLY VERTICAL WELL BASE PIPE MEANS HAVING A LOWER PORTIONTHEREOF FIXEDLY ANCHORED TO THE FORMATION BELOW SAID BODY OF WATER AND APORTION EXTENDING UPWARDLY ABOVE SAID FORMATION, (C) MARINE CONDUCTORMEANS CONNECTIBLE AT ITS LOWER END TO THE UPPER END OF SAID WELL BASEPIPE MEANS WITH THE UPPER END OF SAID CONDUCTOR PIPE EXTENDING ABOVE THESURFACE OF THE WATER IN THE VICINITY OF SAID OPERATIONAL PLATFORM MEANS,(D) BUOYANCY TANK MEANS SECURED TO SAID MARINE CONDUCTOR MEANS BELOW THESURFACE OF THE WATER AND HAVING SUFFICIENT BUOYANCY TO SUPPORT A MAJORPORTION OF THE WEIGHT OF SAID MARINE CONDUCTOR MEANS, (E) WEIGHT SUPPORTMEANS OPERATIVELY SECURED TO SAID MARINE CONDUCTOR MEANS NEAR THE UPPEREND THEREOF AND TO SAID PLATFORM MEANS FOR SUPPORTING THAT PORTION OFTHE WEIGHT OF SAID MARINE CONDUCTOR MEANS UNSUPPORTED BY SAID BUOYANCYTANK MEANS, (F) SAID WEIGHT MEANS CARRIED BY SAID VESSEL AND ARRANGEDFOR SUBSTANTIALLY FREE VERTICAL MOVEMENT, SHEAVE MEANS SECURED TO SAIDVESSEL AT A FIXED LEVEL ABOVE THE UPPERMOST POSITION OF SAID WEIGHTMEANS, CABLE MEANS HAVING ONE END THEREOF SECURED TO SAID MARINECONDUCTOR MEANS, SAID CABLE MEANS PASSING OPERATIVELY OVER SAID SHEAVEMEANS WITH THE OTHER END OF THE CABLE MEANS SECURED TO SAID WEIGHTMEANS, SAID WEIGHT MEANS BEING FREE TO MOVE UP AND DOWN AS THE VESSELRISES AND FALLS DUE TO WAVE ACTION (G) MOVEMENT-LIMITING MEANSPOSITIONED IN CONTACT WITH SAID MOVABLE WEIGHT MEANS FOR CONFINING THEMOVEMENT OF SAID WEIGHT MEANS ALONG A SELECTED PATH, (H) SAIDMOVEMENT-LIMITING MEANS COMPRISING SUBSTANTIALLY VERTICALLY-EXTENDINGRIGID ELONGATED MEMBERS OF A LENGTH AT LEAST EQUAL TO THE MAXIMUMVERTICAL MOVEMENT OF SAID WEIGHT MEANS AND ARRANGED IN CONTACT WITH SAIDWEIGHT MEANS TO PREVENT ANY SUBSTANTIAL LATERAL MOVEMENT THEREOF, AND(I) SAID WEIGHT MEANS COMPRISING VARIABLE WEIGHT TANK MEANS ADAPTED TOCONTAIN WEIGHTING MATERIAL.